Array.prototype.indexOf = function(val) {  
   for (var i=0; i<this.length;i++) { if (this[i] == val) return i; }  
   return -1;  
};  
Array.prototype.remove = function(val) {  
   var index = this.indexOf(val);
   if (index>-1) { this.splice(index,1);}
   return this;
};